pulse rate

[tgo123]

I'm 61 yrs old and my pulse rate during my last checkup was 37...I'm usually around 48.
I have been a runner for 44 years with several 26 mile marathons to my credit. I usually run 6 to 7 days per week and average 4 to 5 miles per run. I usually run over very hilly terrain......I live in San Diego where the weather is generally warmer.........Should i be alarmed? I feel fine, no dizziness or shortness of breath and when I'm done with my runs i feel great.........

[tgo123]

Thanks for your response and as I say, i do feel great...
no water retention as you had mentioned......
Thanks again for your response

[MichelleP_3811]

Did your doctor show any concern?  I think the biggest worry would be if you are struggling at that rate.  If not you may just have a really really well conditioned system.  In any event I would follow up with the doctor to find out what it means for your particular case but I would not get too concerned if you are not having any sort of heart difficulties or duress.  The one thing you may want to pay attention to is if you suspect you are retaining water.  Are your ankles swollen?  If so then do address this with your doctor in conjunction with the slow rate as it could indicate some failure but considering you state you feel fine and even great I suspect you are fine.